Field
The present disclosure relates to an organic light emitting display device and more particularly, to an organic light emitting display device which can be reduced in power consumption and improved in luminance uniformity by minimizing damages to a pixel area caused by laser processing during manufacturing of an auxiliary electrode and a second electrode and improving contact characteristics of the auxiliary electrode.
Description of the Related Art
An organic light emitting display (OLED) device is a self-light emitting display device. The OLED device uses an organic light emitting element in which electrons and holes are injected into an emission layer from an electrode (cathode) for injecting electrons and an electrode (anode) for injecting holes, respectively, and the electrons and holes are combined into excitons. When the excitons transition from an excited state to a ground state, lights are emitted from the organic light emitting element.
The OLED device can be classified into a top emission type, a bottom emission type, and a dual emission type depending on a direction of light emission, and can also be classified into a passive matrix type and an active matrix type depending on a driving method.
The OLED device does not need a separate light source as needed in a liquid crystal display (LCD) device. Thus, the OLED device can be manufactured into a lightweight and thin form. Further, the OLED device is advantageous in terms of power consumption since it is driven with a low voltage. Also, the OLED device has excellent color expression ability, a high response speed, a wide viewing angle, and a high contrast ratio (CR). Therefore, the OLED device has been researched as a next-generation display device.
As high-resolution display devices develop, the number of pixels per unit area has been increased and a higher luminance has been demanded. However, in a light emitting structure of the OLED device, there is a limitation in luminance (Cd) per unit area (A), and an increase in applied current causes a decrease in the reliability of the OLED device and an increase in power consumption.
Accordingly, it is necessary to overcome the limitations in emission efficiency, lifetime, and power consumption of an organic light emitting element that hinder a quality and productivity of the OLED device. Thus, various studies for developing an organic light emitting element capable of improving emission efficiency, a lifetime of an emission layer, and a viewing angle while maintaining a color area are being conducted.
An organic light emitting display device includes an organic emission layer formed between a first electrode (anode) and a second electrode (cathode) facing each other. The first electrode is formed corresponding to each sub-pixel area, and the second electrode is formed commonly corresponding to a plurality of sub-pixel areas.
Unlike the first electrode formed corresponding to each sub-pixel area, the second electrode is formed corresponding to all of a plurality of sub-pixel areas and thus has a higher resistance than the first electrode.
Particularly, if the organic light emitting display device is of top emission type in which a light is emitted along a path penetrating the second electrode, the second electrode is formed of a transparent conductive material as thin as possible to increase the luminance of a pixel area. Thus, the second electrode may have a higher resistance.
That is, due to a high resistance of the second electrode, the luminance uniformity in the pixel area is decreased. Further, power consumption of the organic light emitting display device is increased in order to secure a desired level of luminance.
In order to solve this problem, the organic light emitting display device further includes a separate auxiliary electrode formed of a material having a lower resistance than the second electrode in order to reduce a resistance of the second electrode.
In order to electrically connect the auxiliary electrode and the second electrode, a laser (or other energy source) is irradiated to an auxiliary electrode contact area. Thus, a metal electrode material is melted by heat energy of the momentary laser to form a contact between the auxiliary electrode and the second electrode.
However, due to the laser irradiated to the auxiliary electrode contact area, other areas in a lower substrate, i.e., an emitting area in the pixel area, may be damaged. The present inventors specifically recognized this problem of damage caused by laser processing and have sought to overcome this problem.